gstreamer: Add LTTng tracing support.

* Create bbappend to add LTTng support in gstreamer package.
  PACKAGECONFIG to control LTTng support in gstreamer. Introduced
  new configure option --enable-lttng-tracepoints.

Signed-off-by: Alexander Barabash <alexander_barabash@mentor.com>
Signed-off-by: Noor Ahsan <noor_ahsan@mentor.com>